Process for the manufacture of dredge bucket pins and other similar articles of manufacture



Feb. 10, 1942. R, NETTENSTRQM 2,272,425

PROCESS FOR THE MANUFACTURE OF DREDGE BUCKET PINS AND OTHER SIMILAR ARTICLES OF MANUFACTURE Filed Jan. 2, 1940 INVENT OR.

ATTORNEY 6 Patented Feb. 19, 1942 warren stares PROCESS FOR THE MANUFACTURE OF DREDGE BUCKET PFNS AND OTHER SEMI- LAR ARTICLES OF MANUFACTURE of Delaware Application January 2, 1940, Serial No. 311,986

4 Claims.

The present invention relates to novel processes for working and conditioning metal bodies,

and more in particular to novel processes involving the conditioning and working of a single piece of relatively thick metal stock to produce an article of manufacture formed in part by a relatively thick body and in part by an integral, relatively thin lug or foot extending therefrom.

Among the objects of the present invention is to provide novel processes for conditioning a piece of relatively thick metal stock by the removal of metal therefrom as by cutting or the like to enable the treated stock at the conditioned end thereof to be worked into a relatively thin extension disposed substantially normal to the said body part and formed integral therewith.

The invention in one of its more practical aspects contemplates processes particularly adapted for conditioning and working relatively thick metal stock to provide a dredge bucket pin having a relatively thick cylindrical body part and a relatively thin lug or foot substantially rectangular shaped in cross section integrally formed therewith at the end thereof and extending substantially normal to the said body part.

The dredge bucket pins hereinabove referred to are used in alluvial dredges which are employed the world over in mining a large portion of the worlds gold, most of the worlds tin and a considerable portion of the worlds platinum.

The digging element of these dredges comprises an endless chain of from 80 to 200 buckets ranging in weight from 1000 to 3000 pounds each of which are provided with apertured eyes for receiving the said pins whereby said buckets are secured to one another. In order to prevent rotation or other unauthorized movement of these pins within the apertured eyes of the buckets, each pin is provided with a foot or lug adapted to cooperate with certain mechanism of the buckets which includes a recess and, if desired, a wedge assembly cooperating with the lug or foot.

Because of the particular environment in which these pins are used, the same are not only subjected to enormous bending and torsional stress, but also to severe abrasion and wear, thus requiring frequent replacement. Because of the conditions under which these pins are used, and

because of the fact that the entire success and safety of the digging operation depends upon the ability thereof to stand the shock and to provide suitable resistance to wear, the workmanship required in order to produce these pins which are capable of withstanding the severe requirements is most exact.

Although pins of composite construction have been used, nevertheless it has been found that the most satisfactory pin construction is one of integral construction with the laterally extending lug formed as a part of the main body at the end thereof. standardized as acceptable parts for dredge line bucket assemblies of the type herein contemplated. However, prior to the present invention all processes followed in manufacturing such pins have involved shaping and conditioning of metal stock under open frame forging machines,

:- wherein said pieces of metal stock are shaped to size by manual manipulation of the billets beneath the hammer'of such machines. Inasmuch as certain present-day practices proceed in their initial stages with rectangular shaped billets, it can be well appreciated that considerable time and effort, as well as technical skill, are required in forming these billets to shape while hot under the said open frame forging device. Furthermore, present manufacturing processes include cumbersome and unwieldy operations when one is reminded of the fact that these pins may weigh as much as 500 pounds and are very likely to have a maximum diameter of 8 with a laterally extending lug of much smaller dimension, as for example, 2" in thickness, and a length from the face of the pin of about 11". According to one of these prior processes, the metal is worked under the said forging hammer from the rectangular shaped billet to the round to form the main body part or" the pin and to provide a lip or tail at one end thereof having sufficient metal to form the laterally extending lug or foot. This lip or tail part, under successive blows from the forging hammer and by proper manipulation by the operator, is gradually bent laterally to the main body part to form in the rough the said lug or foot. Other known processes involve operations which bend and distort the metal stock during the formation of the laterally extending lug requiring additional operations to straighten the same preliminary to machining and finishing, thus increasing the cost and decreasing production capacity. Although there are a large num ber of disadvantages in such operations, such as the excessive amount of labor and machine time, lack of uniformity in dimensions and grain flow in successive articles, the large amount of waste material which must be removed by machining from the rough forgings, and the fact that these forging operations necessitate for completion a Accordingly, such pins have become I number of heats to properly condition the said stock, nevertheless these methods are the only ones known in the art for making such pins, and inasmuch as purchasers have demanded, because of structural requirements, pins of such integral construction, forgers generally have accepted such practices, with the result that such pins are rather costly items to the purchasers.

Recognizing the disadvantages hereinabove enumerated in connection with present processes of making such metal articles as dredge bucket pins and the like, the present invention has proceeded upon the theory of producing such pins of integral construction at greatly reduced cost from the standpoint of material, labor and machine time, and the evolved processes herein disclosed embrace certain procedural steps which greatly decrease the cost of such articles, yet producing uniformity of successive products wherein proper structural requirements are fully met in accordance with the practices in the field. As indicative of the distinct advantages inherently characterizing the present invention, it may be fairly stated that dredge bucket pins and the like possessing qualities as herein enumerated may be manufactured at only from 30 to 50% of the cost of dredge bucket pins made in accordance with present known processes.

The present invention embodies as a princip object certain steps which condition and work relatively thick metal stock to enable the formation of substantially a right-angle or normal extension to be formed therefrom which is relatively small as compared to the stock from which the same is made. This procedure in conditioning and working thick and heavy metal stock to provide a relatively thin lug or foot extending substantially normal thereto was evolved only with the many metal-working difficulties in mind which would normally be expected in providing from a relatively large and thick piece of metal an extension of less thickness at an abrupt or sharp angle thereto. For example, the present invention comprehends conditioning steps in the said processes which permit or enable these relatively thin lateral extensions to be formed from relatively thick stock without scarcity of metal on the outside curvature of the bend, which would otherwise cause cracks, fissures or other imperfections, as Well as an excess of metal on the U inside of the bend which would normally result in such operations performed on heavy stock of the kind herein contemplated. A further desideratum of the present invention in respect of this heavy and thick metal stock is to provide uniformity in grain structure of successive articles at and adjacent the lateral extensions and wherein the grain flow is substantially of a uniform character from the relatively thick part of the article to and longitudinally of the said lateral extensions, thus providing metal characteristics fully able to withstand the stresses and strains to which the same are subjected in the dredge line bucket assemblies in which the same are used.

The invention embracing the novel process for metal working is grounded upon the theory of avoiding hand work incidental to prior processes and to condition the metal stock from which the bucket pin or similar article is to be made to adapt the same for forging operations, thus eliminating to a large degree manual operations and handling of the particular stock material.

Still another object of the present invention is to provide a novel process including the step of conditioning relatively thick and massive metal stock, as hereinbefore referred to, to form a reduced end section having a volume of metal conforming substantially to that required for the laterally extending lug formed therefrom.

More particularly, the present invention includes among its objects the idea of providing a process wherein the metal conditioning step to produce the said reduced end section of a volume required for said laterally disposed lug is accomplished by a cutting or metal-removing operation, as by means of an oxyacetylene torch or the like, whereby the reduced end section is adapted for further metal-working operations in accordance with the invention, without additional or auxiilary processing.

Still a further object of the present invention is to provide a novel process embracing within its scope the step of conditioning the thick and massive metal stock of substantially the diameter required for the main body part of the pins by severing and metal-removing operations intermediate its ends, as by means of an oxyacetylene torch or the like, whereby the desired contour and volume of metal for the said reduced sections are provided to facilitate further metal-Working operations, and wherein the volume of metal for the said end sections is substantially equal to that required for the lugs, thus substantially reducing waste material and expensive machining to produce the finished product.

As a further object of the invention and as a most likely preferred conditioning step in the herein described processes, stock material may be cut or otherwise severed intermediate the ends thereof to provide symmetrically disposed reduced end sections for the stock material on each side thereof whereby the said original piece of stock material is formed into two pieces each of which, when further worked, produces a dredge bucket pin, thus greatly reducing waste material in forming the reduced end sections. In accordance with this aspect of the invention, consideration has been given to the form of cut to provide the said symmetrical end sections, and in accordance with one of the preferred methods of forming these bucket pins the severing of this metal stock takes place by way of a sinuous cut from one side of the metal stock to the other whereby the reduced end sections formed thereby on the adjacent and oppositely disposed parts thereof are of such a shape that the laterally disposed lugs of the finished product can be readily formed with proper flow of metal from the main body part of the pin to and throughout the said lugs.

As an alternative conditioning step, all within the scope of the present invention, said metal stock may be out intermediate its ends to provide two pieces of stock material having symmetrically arranged reduced end sections with a volume of metal therein conforming substantially to that required for the said laterally extending lugs, said conditioning involving in its application removal of metal from the metal stock at the point of severance to proportion the and sections in conformity to the volume of metal required by the lugs to be formed therefrom.

The present invention also embraces within its scope Process steps intimately co-related and c0- ordinated to any one of the conditioning steps above described involving the heating of the end section and adjacent body part of the metal stock preparatory to steps which form the completed article. The present invention therefore contemplates such heating of the metal stock, followed by a subsequent working step of applying pressure to the end section to bend the same laterally of the main body part and which step is followed by a metal-working step wherein the end section is subjected to a die-forging operation to further bend the end section into substantially normal relation to the main body part and to shape the same to the form of the laterally extending lug.

In accordance with the present invention, the processes herein described are predicated upon a desire to eliminate Waste material and excess labor and machine time in the formation of these articles of manufacture, and accordingly the said invention embraces within its scope certain steps whereby the pins may be formed in such a condition that very little machine or finishing work is required thereon.

Other objects, features, capabilities and advantages are comprehended by the invention, as will later appear and as are inherently possessed thereby.

Referring to the drawing:

Figure 1 is a View in side elevation of metal stock which may be used in forming the article in accordance with the present invention and disclosing more in particular a method of treating the same to condition it for further metalworking operations;

Figure 2 is a view in side elevation of metal 1':

stock which may be used in connection with the present invention disclosing an alternative conditioning cut preparing the same for further metal-working operations;

Figure 3 is a view in side elevation of metal z.

stock conforming substantially to that shown in Figure 2'and disclosing still a further alternative conditioning cut preparing the same for additional working operations in accordance with the present invention;

Figure 4 is a View in side elevation of the metal stock after an intermediate metal-working operation;

Figure 5 is a view in end elevation of the metal stock shown in Figure 4;

Figure 6 is a view in side elevation disclosing a dredge bucket pin or similar article made in accordance with the present invention;

Figure 7 is a view in end elevation of the pin shown in Figure 6 of the drawing; and

Figure 8 is'a fragmentary view in side elevation of a dredge bucket disclosing a pin, such as shown in Figure 6, in its operative association therewith.

Referring now more in detail to the drawing, 1

the present invention relates to articles of manufacture such as dredge bucket pins, generally all referred to as l, shown for example in Figure 5 of the drawing, and comprising a relatively thick and massive main body part 2 and a relatively small and thin laterally extending lug d, the said body part 2 being cylindrical in shape and the said lug 4 being substantially rectangular or of any other desired shape to conform to design requirements. As shown in Figure 6 of the drawing, such a pin I is disclosed in its associated relation with a dredge bucket 6 formed with spaced apertured ears, such as 8, which receive the main body part 2 of the pin whereby the pin is adapted to secure an adjacent bucket to the one disclosed in a dredge line bucket assembly used in dredging operations and the like. These buckets are of massive construction adapted for heavy dredging operations, and accordingly the main body part 2 of the pin is of considerable diameter to withstand the exceedingly large shearing stresses and strains to which subjected and to provide a suitable bearing connection between the adjacent buckets of the assembly. Because of theheavy type of equipment with which these pins are used, diameters up to a maximum of 8" are not unusual. In an assembly of this kind, it is essential to maintain the pin in its operative position with the said adjacent buckets, and accordingly the lug l of the said pin is received within a recess it) formed in the outer face of one of the ears 8 and which lug may cooperate through some suitable locking device, such as the wedge mechanism l2, to prevent rotational movement of the pin in respect of the ears *3. As referred to hereinbefore, because of the stresses and strains to which the said pin is subjected, it is essential that the same be formed to include an integrally constructed lug or foot in order to secure the desired strength for resisting shear and other forces acting thereon.

According to prior practices, a large amount of machine and finisl'nng work would have to be done on the rough forgings to produce the completed article, such as the pin shown in Figure 5 of the drawing. Furthermore, in accordance with these prior practices there is no assurance that grain flow will be uniform from the main part of the pin to the lug or foot without abrupt changes and longitudinally of the said lug or foot inasmuch as the character of metal structure at the junction of the lug and main body part, as well as within the lug itself, is dependent entirely upon the manual manipulation of the stock under the impact blows from the forging hammer in the formation of the lug or foot. Furthermore, there is no uniformity in the size of successive pins made in accordance with such pro: cedure. Due to the weight of the particular article being formed, it can be well appreciated that considerable time and effort are necessary in fabricating the pin and that even when finished in the forging machine each piece must be machined separately, and in most cases a large amount of material has to be removed in order to produce the finished product.

The present invention involves procedural steps which, when followed, result in a uniformity of product at greatly reduced cost in terms of material, labor and machine time, the said processes contemplated in accordance with the present invention embracing within their scope certain procedural steps which lead to uniform flow of metal in successive articles with attendant advantages from such construction.

The process in its broadest aspect involves conditioning of a piece of metal stock, as by way of cutting or metal-removing operations, so as to form an end section which may be worked into substantially normal relation to the main body part thereof to produce a laterally extending lug. Illustrative of this procedure, reference is hereby made to Figure 1 disclosing metal stock l8 substantially of cylindrical formation and of a diameter conforming substantially to the diameter of the finished product, which metal stock is out along the line 2% or material 22 removed in any other desired way to produce an end section 24 for said metal stock which is processed as will be later hereinafter more fully disclosed. Although this end section may be formed by a cut of any desired contour, nevertheless' the preferred form is sinuous or ogeeshaped including curved parts 26 and 28 cone nected by way of a cut 38 longitudinally disposed in respect of the metal stock. This preferred form of cut provides an end section of the desired metal content to form the lug, although it will be clearly appreciated that said out may consist merely of the two curved parts 26 and 28 which will result in a sinuous cut of the desired formation.

Although the present invention may be practiced by conditioning metal stock in the manner disclosed in Figure l, nevertheless the conditioning in accordance with Figure 2 is the preferred way in that by a single cut 36 two pieces of metal stock 32 and 34 are prepared without waste material. The cut 35 conforms substantially to that shown in Figure 1 and includes the curved portions 38 and 40 connected by way of the straight portion 42 therebetween. In accordance with this procedural step, such pieces of metal stock 32 and 34 are formed with end sections 4 and 48, respectively, providing metal for the formation of the laterally extending lugs in accordance with the invention, as will be hereinafter more fully disclosed. The cuts of Figures 1 and 2 are preferably made by means of an oxyacetylene torch or the like moved in accordance with any pattern that may be used for regulating the speed of travel and direction to give the desired contour to the out, said out being made while the metal is in its cold state.

Where further economies are desired in the finishing and machining operations hereinafter referred to, and where a out such as shown in Figure 2 leaves symmetrically arranged end sections for the metal stock 32 and 34 containing more material than actually required for the lug 4, the cut of Figure 2 may be somewhat modified, as shown in Figure 3, wherein metal stock is out along the lines 48 and 5.) to provide metal stock 52 and 54 having end sections 56 and 58, respectively. The cuts 48 and 50 are sinuous or ogeeshaped conforming substantially to the cut 36 of Figure 2 except that the curved parts thereof are formed from radii varying in length, but the said cuts are symmetrical in that by the removal of the material designated as 6D the two end sections 56 and 58 have a substantially uniform metal content resulting in lugs conforming substantially in size and requiring substantially the same amount of finishing and machine work as the other. In following this cutting operation according to Figure 3, either of the cuts 48 or 50 may be initially performed upon the entire metal stock used to provide the stock material 52 and 54, after which the other out may be made to remove the metal body 60.

After the metal stock has been conditioned by way of the cutting or forming operation explained in connection with Figures 1, 2 and 3, the end section and adjacent body part are heated to the required temperature to facilitate the next successive steps in the formation of the particular article. After heating of the said parts. the metal stock is introduced into an upset forging machine having one set of dies adapted to grip the body of the metal stock, while a forming die moves in a direction substantially parallel to the longitudinal axis of the stock to bend the end section into angular relation with respect to the main body part, as shown in Figure 4 of the drawing. These gripping dies cooperate with the metal stock over a considerable portion of its length from and adjacent the end section to prevent twisting, distortion, or other lateral displacement which would otherwise occur when the forging blows are delivered to said end section. This bending operation is facilitated by the particular curvature of the cut defining in part the end section of the metal stock in that the bending is initiated by contact of the die member with the curved surface at the end of the end section.

After the end section has been bent into the position as shown in Figure 4, the same is removed from the first set of gripping die members and placed between another set of dies adapted to grip the same adjacent the end section in the manner above described for a die-forging operation. Upon operation of the die-forging mechanism, gripping of the body part takes place, whereupon a forging blow is delivered to the end section in a direction substantially parallel to the longitudinal axis of the stock to form the lug 4 from said material constituted by the end section within the confines of the die members of the said machine. The material is then released for further finishing and machining operations.

In accordance with the above procedure, it is possible to use metal stock having a diameter closely approaching the diameter of the finished pin inasmuch as no manual manipulation is necessary within an open frame forging device in order to form the particular article. Furthermore, the end section of the metal stock is so formed as to facilitate bending and die-forging operations to produce the finished lug therefrom, the said cut or forming thereof being such that in the finished article continuity of flow of metal from the main body part to and within the lug is accomplished as has been evidenced by etchings made of cross sections of material taken from the lug 4 and body part 2. Where desired, material may be cut or formed as disclosed in Figure 3 of the drawing, whereby the volume of metal in the end sections more closely approaches the metal requirements of the lugs 4 in their finally finished form. Thus, machining and finishing operations are decreased considerably, resulting in lower costs than would otherwise be experienced.

The present invention, as hereinbefore described but again pointed out for emphasis, has to do with a process of forming an article having a relatively thick and massive main body part and a relatively small and thin laterally extending lug of integral construction. Heretofore, hand operations have been required to condition the metal stock in order to form the laterally extending lug, but in accordance with the present invention, these large diameter pins with the attendant weight and mass of metal used can be successfully and uniformly formed by a die-forging operation resulting in uniformity of structure and grain flow. As a material part of this invention instrumental in permitting die-forging operations on an article of the size and character of the one herein disclosed, reference is made to the conditioning of the metal stock preparatory to the bending and forging operations. This cutting or forming of the end sections in the manner disclosed is at least in part instrumental in facilitating the bending and die-forging operations in two successive steps to form the completed article where the metal stock is of the size herein contemplated. The present process accordingly leads to economies in manufacture and uniformity of product heretofore unknown in the art, and results in improvements in the structure involved.

While I have herein described and upon the drawing shown illustrative embodiments of the invention, it is to be understood that the invention is not limited thereto nor to the particular process steps described, but that it may comprehend other constructions, arrangements of parts, details and features, as well as other process steps, without departing from the s irit of the invention.

I claim:

1. The process of producing an article of the character described having a substantially cylindrical main body part and a laterally disposed substantially rectangular shaped lug wherein the diameter of the said body part exceeds the thickness of said lug, comprising the steps of removing approximately a semi-cylindrical section from a billet of relatively massive metal stock to leave an approximately semi-cylindrical end section, heating said end section and adjacent stock, bending said end section angularly with respect to said stock while in said heated condition, and subjecting said end section to a die-forging operation to bend the same into substantially normal relation to said stock and to form said lug.

2. The process of producing a dredge bucket pin having a cylindrical shaped main body part and a laterally disposed substantially rectangular shaped lug wherein the diameter of the said body part exceeds the thickness of said lug, comprising the steps of severing a billet of massive metal stock of slightly greater diameter than required for said body part by means of a torch forming a sinuous cut therethrough to provide two pieces of stock each having an end section of reduced thickness extending from the severed end thereof, heating the end section and adjacent body of one of said pieces, bending said end section 'angularly with respect to said stock while in said heated condition, and subjecting said end section to a die-forging operation to bend the same into substantially normal relation to said stock and to form said lug.

3. The process of producing a dredge bucket pin having a cylindrical shaped main body part and a laterally disposed substantially rectangular shaped lug wherein the diameter of the said body part exceeds the thickness of said lug, comprising the steps of cutting a billet of massive metal stock obliquely with respect to its longitudinal axis and while cold by means of a torch to provide an end section of reduced thickness extending from the end thereof, heating the end section and adjacent body of said stock, bending said end section angularly with respect to said stock by application of a forging blow to said end section substantially parallel to the longitudinal axis of said stock while the same is in said heated condition and is held against lateral displacement, and subjecting said end section to a dieforging operation wherein a forging blow is applied to said end section substantially parallel to the longitudinal axis of said stock while said stock is held against lateral displacement to bend said end section into substantially normal relation to said stock and to form said lug.

4. The process of producing an article of the character described having a substantially cylin drical main body part and a laterally disposed substantially rectangular shaped lug wherein the diameter of said body part exceeds the thickness of said lug, comprising the steps of severing a billet of massive metal stock intermediate its ends while cold to provide two pieces of stock each having an approximately semi-cylindrical end section, heating the end section and adjacent body of one of said pieces, bending said end section angularly with respect to said stock while the same is in said heated condition and is held against lateral displacement, and subjecting said end section to a die-forging operation while said stock is held against lateral displacement to bend said end section into substantially normal relation to said stock and to form said lug.

ARTHUR R. NETTENSTROM. 

